Exam #2Ch 142 Name______________________________Use the following if necessary:R = 8.314 J/moleK the universal gas constant. Kspa = [M+2][H2S]/[H+]2 for sulfideprecipitates.Part I Multiple Choice. Five points each.1. Which of the following solutions will Silver nitrate be the least soluble in? a. 0.1 M NaOH b. 0.1 M NaCl c. 0.1 M NaBr d. 0.1 M NaNO32. Which of the following could represent the titration curve for the titration of sodium sulfite (Na2SO3) with hydrochloric acid? a. c. b. d.3. T F The process H2(g) + C2H4(g)  C2H6(g) would have its equilibrium constant decrease with increasing temperature.4. Which compound, if formed as a precipitate, would not be redissolved by adding acid to it?1a. Ag2CO3b. AgOH c. Ag3PO4d. AgBr5. Which process, of those below, is always spontaneous?a. ΔS >0, ΔH >0b. ΔS <0, ΔH<0c. ΔS<0, ΔH>0d. ΔS>0, ΔH<06. Which process has a positive entropy change?a. 5.0 liters N2(g), 0oC → 10.0 liters N2(g), 0oCb. water/benzene mixture → separated water and benzenec. Fe(s), 100oC → Fe(s), 0oCd. phenol(l) → phenol(s)7. T F For the reaction; NH4+(aq) + OH-(aq) → NH3(aq) + H2O(l), the Gibbs free energy change is ΔGorxn = -52.8 kJ/mole. Therefore, one can expect theequilibrium constant to be large (ie. bigger than one)8. What is ΔGorxn for the reaction AgOH(s) → Ag+(aq) + OH-(aq) at 25oC? (Hint: youwill not be able to calculate it from thermodynamic tables)a. –5.8 kJ/mole b. –43.9 kJ/mole c. +5.8 kJ/mole d. +43.9 kJ/molePart II Short Answer. 9. Rank the solutions below in order from the one zinc phosphate will be least soluble in (#1) tothe one zinc phosphate will be the most soluble in (#4) (5 pts)0.50 M KBr 0.50 M KCN 0.50 M K3PO40.50 M NH3 10. Give an example of a specific phase change or reaction which has a negative entropy change,2but which is nevertheless spontaneous. Be specific about the temperature conditions under whichit is spontaneous (ie. high or low temp) (5 pts)11. Do sulfide precipitates tend to be more soluble at low pH or at high pH? Explain why. Mostof the credit for explaining why. (5 pts)12. Explain the phrase “life is an apparent contradiction of the second Law of thermodynamics.” Explain both why someone might say it, and why it actually is not a correct statement. (ie how living things get around the problem you just pointed out) (6 pts)Part III Solved problems. Show all your work. Points as stated.313. a. What would be the Co+2 concentration in a solution made by adding 6.0 g of ethylenediammine (symbol en, formula C2N2H8) to 50 ml of 0.20 M cobalt(II)nitrate? (6pts) b. What mass of cobalt (II) hydroxide will dissolve in 500 ml of 0.50 M ethylenediammine (en)? (6 pts) 14. a. Calculate the molar solubility of zinc hydroxide (just plain old straight zinc hydroxide) (5pts).4b. Zinc nitrate is soluble in water at a pH of 2.0, only very slightly soluble at a pH of 9.0, but soluble again at a pH of 13.0. What is the deal here (ie. explain carefully why)? (5pts) c. For example, calculate the solubility of zinc nitrate at pH = 9.0 (5 pts) d. For a further example, calculate the solubility of zinc nitrate in a 1.00 M solution of NaOH. (ex cr)15. For the titration of 30.0 ml of 0.100 M lactic acid with 0.100 M potassium hydroxide, calculate;5a. the pH at the beginning.(4 pts)b. the pH after adding 15.00 ml of base. (4 pts)c. the pH after adding 10 ml of base. (4 pts)d. the pH at the endpoint. (4 pts)e. the pH after adding 32 ml of potassium hydroxide. (4 pts)f. Sketch the titration curve. (3 pts) 16. For the vaporization of hydrazine:N2H4(l) → N2H4(g)6a. Calculate the (approximate) boiling point. (4 pts)b. Calculate ΔGovap and the vapor pressure of hydrazine at 25oC. (5 pts)c. Same as b. except at 75oC. (5 pts)d. Calculate ΔG (not ΔGo) for the reaction at 25oC, if the pressure of hydrazine gas is 5.0 torr. Based on your answer, will the reaction shift to the right or to the left? (ex cr)17. Using calculations, find a pH which will separate a solution which is 0.050 M in both Co+2 and Fe+2 in a solution which is 0.10 M in H2S. Be specific about which precipitates out and which will remain in solution at this pH. (ex